On October 30, 1964 NASA research pilot Joe Walker climbed into a very strange contraption. The machine was called the Lunar Landing Research Vehicle (LLRV) or sometimes the "Flying Bedstead." The spindly, four-legged research craft was designed to simulate the conditions astronauts would find when landing. The Moon only has one-sixth of Earth's gravity and there is no atmosphere to create drag, so the final landing had an almost vertical approach with the speed controlled by a rocket engine.
The main engine of the LLRV would lift it to test altitude and then be throttled back until it only supported five-sixths of the craft's total weight. The craft and pilot would then be subjected to conditions similar to those they would experience on the Moon. Walker demonstrated this principle on three flights on that first day of testing. As Neil Armstrong, the first astronaut to land on the Moon said, "the mission would not have been successful without the type of simulation that resulted from the LLRVs."